As is known to persons skilled in the art of braking rotation members such as automotive vehicle wheels, where brake modulators are used for varying the braking effect exerted, it is necessary to sense the rate of change of changing rotational speeds of a rotatable element. Other examples of such needs are known to persons skilled in the applicable arts. A variety of approaches to sensing rates of change of changing rotational speeds and/or vehicle wheel slip have been proposed heretofore, including certain prior sensors disclosed by the inventor of the sensor described hereinafter.
In connection with the development and use of sensors of the type briefly described hereinabove, one line of development has been directed to sensors having a flyweight coupleable for rotation in response to wheel rotation and decoupleable in response to the exertion on the flyweight of a torque arising due to a change in rotation of a vehicle wheel. In such sensors, it has now become known to provide a control means operatively connected with a flyweight for exerting thereon torques resisting decoupled rotation of the flyweight and a signalling means such as an electrical switch, which may preferably be of a magnetically actuated type, such as a reed switch or a Hall effect semiconductor, responsive to decoupled rotation of the flyweight for signalling occurrences of an excessive rate of change in changing rotational speeds of the wheel. Those forms of sensors which have achieved particular success in accommodating a wide range of vehicle operating conditions have done so, at least in part, by providing an improved control means capable of applying a torque which is an average of a plurality of different torques individually applied in a rapidly fluctuating series. Such sensors, while successful, may under certain operating circumstances and in certain systems require insertion of special electrical circuits or the use of other special components in order to accommodate generation of signals as a train of rapidly fluctuating pulses.